The present invention relates to sheet sorters, collators or receivers having a plurality of receiving trays into which successive sheets are fed from a copier, printer or the like source of printed sheets to be collated and assembled or finished in integrated sets by means of an in-bin stapler or finished operable for movement between an out of the way position permitting the feeding of sheets into the receiving trays and an operative position for in situ finishing or stapling of the collated sets, prior to removal of the sets from the trays.
The problems of stapling in combination with collating sets of sheets differ, depending upon the nature of the collator. For example, when the collating trays are disposed in fixed stacks, spaced vertically to receive a selected number of sheets in sets in the trays, it is a relatively simple task to mechanically remove sets of sheets from the trays and transport the sets to a stapling station or finishing station or to move the trays from a sheet receiving position to a sheet stapling or finishing position at which the sets are bound.
In recent years, collating or sheet sorting machines have been developed for use in conjunction with reproducing machines i.e., photocopying or printing machines, wherein the collators or sorters are of a compact configuration, having trays which are mounted so as to be shifted from positions above and below a sheet entry location at which sheets are fed from the reproducing machine, or at the discharge location of a sheet transport, at which the trays are spaced relatively far apart to facilitate entry of a desired number of sheets. At the positions above and below the sheet entry location, the trays may be close together and can compact the sheets into a reasonably tight set.
These moving bin sorters or collators provide limited space for the purpose of installing a stapler, and the closely spaced relationship of the trays, in all but the sheet receiving position, renders difficult application to the structure of an automatic stapler for in-tray stapling of the sets.
Prior devices have been developed, however, for in-tray stapling of collated sets, in a number of ways. Typical moving tray sorters have the trays extended upwardly on an incline in the direction of sheet movement into the trays and the trays are actuated by a suitable cam to vertically move the ends of the trays proximate the sheet entry between positions below the sheet entry to above the sheet entry so that the height of the space between trays at the sheet entry location is determined by the profile of the cam.
U.S. Pat. No. 4,928,941, granted May 29, 1991, to Nobutaka Uto, et al discloses one example of a sorter combined with a stapler which is shiftable from a position out of the path of sheets entering a tray to a position at which the anvil of the stapler is moved to a position below the set of sheets and the stapler body occupies space caused by the inherent longitudinal displacement of the trays above the sheet receiving tray, as the inclined tray moves from below to above the sheet entry location. The longitudinal displacement of the superposed trays provides space for the stapler body, even though the trays are not sufficiently vertically spaced to provide space for the stapler body. Such a construction requires adequate longitudinal displacement of the trays above the tray in which stapling is performed to assure adequate margin for stapling.
U.S. Pat. Nos. 4,687,191, granted to Stemmle and 4,681,310, granted to Cooper, disclose moving tray sorters of the type wherein the trays are spaced apart to receive sheets and are close together above and below the sheet entry location. In these prior devices, the tray shifting or indexing means are constructed to cause the trays to provide a space or spaces in addition to the normal sheet receiving spacing of the trays, whereby the stapler may be moved from a position clearing the paper path at the sheet inlet to a position at which the anvil and body of the stapler are accommodated by the additional spaces between trays.
On the other hand, the need for providing space for the stapler may be obviated in the case that the tray may be shifted to the stapler, as seen, for example, in Kramer et al U.S. Pat. No. 4,925,171, but such structure is large and not generally applicable to today's type of small sorters. As indicated above, the mode of operation can be accomplished simply in the case of such vertically spaced and fixed trays which can be translated horizontally to or from a stapler.
Also, it is known to use certain tray shifting cam mechanisms, having dual cams and guides which direct the course of the tray ends proximate the sheet inlet location, so that the trays are moved horizontally, opposite to the direction of sheet infeed into the stapler throat between the anvil and the body of a fixed stapler which is not restrained in its application to a set of sheets by the path of sheets into the trays during normal sorting or collating of the sheets.
In all of these set stapling or binding operations, there is a problem of stapling efficiency if the set of sheets is not in a compact and neat order during staple penetration when the stapler is activated. Transfer devices which grip the set of sheets, transfer the set to an out of the way stapler and deposit the sets in a receptacle, as seen in Noto U.S. Pat. No. 4,361,393, for example, are quite efficient due to the clamping action of the transfer device on the sets. However, such machines, usually referred to as finishers, either in association with a collator on a reproduction machine or used for off-line collating, are large and expensive, and do not lend themselves to advantageous use in conjunction with typical, small compact sorters used in combination with photocopying machines, such as the sorter disclosed in Lawrence U.S. Pat. No. 4,911,424, or other compact sorters such as that shown in Lawrence U.S. Pat. No. 4,343,463, or DuBois and Hamma U.S. Pat. No. 4,328,963 as examples of sorters of the type with which the present invention is concerned.
In Lawrence U.S. application Ser. No. 730,746 filed Jul. 16, 1991, of common ownership herewith, there is disclosed an apparatus which, in a moving tray sorter, grips collated sets in the trays and partially backs the sets out of the trays in the opposite direction from the infeed direction, transfers the trailing edge of the set to a stapler and then returns the stapled set to the trays successively. The gripper and the stapler are arranged so as to not interfere with the sheet infeed.
In Morii, et al, U.S. Pat. No. 4,971,302, there is shown an example of set gripping and partial removal from a side of the tray, not the infeed end of the tray, and returned to the trays by gripping and stapling means disposed off to one side of the trays and occupying a large space at the side of the sorter.